It is routine practice in biotechnology and biomedical laboratories to store cell lines, DNA libraries, tissues, viruses, bacteria, fungi and other biological specimens, biochemical agents, blood and body fluids in cryogenic and freezing environments for the purpose of better preservation for extended periods of time, up to 15-20 years or more. In the biomedical and biotechnology fields, proper and secure labelling and identification of containers and objects carrying these types of biological substances are pivotal for daily research and clinical operations. Other industries also require labelling of containers and objects that must be frozen or labelling of already frozen surfaces such as liquefied gas pipes and transportation pipelines and objects in a freezer.
There are cryogenic adhesive labels available which can be printed with various types of printers. Thermoplastic labels for cryogenic storage containers which can be inscribed by various writing instruments and/or printed in laser printers are described, for example, in U.S. Pat. Nos. 5,836,618 or 7,108,909. One of the issues associated with cryogenic pressure-sensitive labels is that they are not effective when applied onto frozen surfaces for example vials, boxes, cans or other containers, or when below low temperature limits. It is a well known fact that adhesive labels do not adhere well to cold surfaces. Cryogenic labels such as 3M label material 7604FP in manufacturer's datasheet specify that “Low temperature surfaces, below 50 F (10 C), cause adhesive to become firm and will not allow to develop intimate adhesive contact”. Even the efforts to wipe off the condensation prior applying the label do not allow proper label adhesion. As a result the labels do not adhere to frozen container and detach immediately or shortly after the adhesion. The prior art of identification of cryogenic containers is related to adhesive labels.
Very often it is required to label or re-label vials and other containers which are already stored in cryogenic or freezer environment such as liquid or vapour phase liquid nitrogen, freezer, dry ice, Alcohol-dry-ice bath and other low temperature conditions when the container has a surface temperature around −70° C. or well below. Applying an adhesive label or a tape to frozen surface is significantly different from applying them at room temperature. As a matter of fact the surface temperature is determinative as to whether the adhesive will succeed or fail. For a long time this problem has not been solved. Sealing and labeling of frozen containers is a problematic procedure due to the fact that the adhesive labels and tapes cannot stick to frozen surfaces, as the adhesive and the material properties change in such low temperatures. For example, many thermoplastic films such as vinyl, polypropylene, polyethylene, polyester, polystyrene, etc. become brittle and crack in cryogenic temperatures. There is a wide variety of containers used in laboratories including but not limited to vials, tubes, polycons, culture plates, racks, canes, goblets, plastic bags, blood bags, IV bags, bottles, flasks, microscope slides, boxes, cassettes, tubing and hoses, etc.
Often samples are stored inside screw-cap vials inside cryogenic boxes supported by racks (metal or plastic), in the liquid phase of liquid nitrogen. It is known that liquid nitrogen can penetrate the vials through bypassing the cap threads or sealing rings of the vial caps. As a result the liquid nitrogen can be a carrier of contaminants and cross contaminate samples inside the liquid nitrogen tank.
Another negative aspect of using adhesive labels is some low level toxicity of adhesives that can accumulate inside liquid nitrogen tank. There may be some concerns that the adhesive toxicity might have some effect on biological materials in cryo storage.
Yet another important aspect of sample storage or storage of other sterile solutions, cell growth media and liquids is to avoid contamination. As a standard operating procedure in cell culture labs and other types of labs the containers or certain parts thereof (caps, stoppers, bottles or even entire container) are sprayed with alcohol or other disinfectants. It prevents contamination for a short period but the contamination may happen after the evaporation of the disinfectant.
The challenge is that many material properties are affected when they become wet with alcohols and solvents, e.g., adhesives cannot stick to wet alcohol surface on the vials, or siliconized containers or oily surfaces. Other chemicals also affect surface adhesion.
Yet another important issue is that adhesives do not stick well to metal containers inside freezers or liquid nitrogen storage. The vast majority of cryo labels will fall off if they are applied to metal with a subsequent storage inside −70° C. freezer or liquid nitrogen. Furthermore, labelling of a frozen metal is a challenge in the biopreservation industry because properties of a frozen metal are different compared to properties of a frozen plastic. Labelling of frozen metal may be more difficult compared to frozen plastic labelling. Cryogenic temperatures may make materials brittle and crack.